The present disclosure includes a transmission comprising a first wheel assembly including a first wheel, a first drive gear coupled to the first wheel such that driving the first drive gear causes a corresponding rotation of the first wheel, and a first motor coupled to the first drive gear to drive the first drive gear. The transmission also includes a second wheel assembly that includes, a second wheel, a second drive gear coupled to the second wheel such that driving the second drive gear causes a corresponding rotation of the second wheel, and a second motor coupled to the second drive gear to drive the second drive gear.

The present disclosure includes a transmission comprising a first wheel assembly including a first wheel, a first drive gear coupled to the first wheel such that driving the first drive gear causes a corresponding rotation of the first wheel, and a first motor coupled to the first drive gear to drive the first drive gear. The transmission also includes a second wheel assembly that includes, a second wheel, a second drive gear coupled to the second wheel such that driving the second drive gear causes a corresponding rotation of the second wheel, and a second motor coupled to the second drive gear to drive the second drive gear.

A frictional roller reducer having a sun roller; a ring roller; a plurality of intermediate rollers having rolling surfaces coming in rolling contact with the sun roller and the ring roller; the sun roller or the ring roller having a pair of roller elements including inclined surface portions on a circumferential surface coming in rolling with rolling surfaces, the inclined surface portions inclined in directions going toward the intermediate rollers in a radial direction as going away from each other in the axial direction; a pressing device pressing the pair of roller elements in directions going closer to each other, and an elastic member arranged between the pair of roller elements, the elastic member urging the pair of roller elements in directions going away from the rolling surface of the intermediate rollers.

A portable semi-trailer landing-gear motor system and method for use in raising and lowering landing gear on a variety of different semi-trailers by motorized turning of the various-sized drive shafts of the landing gears in appropriate opposing directions, providing motorized performance of an otherwise physically difficult procedure, providing transportability and easy storage within a tractor or truck for use on a variety of semi-trailers in various locations and under various conditions.

A portable semi-trailer landing-gear motor system and method for use in raising and lowering landing gear on a variety of different semi-trailers by motorized turning of the various-sized drive shafts of the landing gears in appropriate opposing directions, providing motorized performance of an otherwise physically difficult procedure, providing transportability and easy storage within a tractor or truck for use on a variety of semi-trailers in various locations and under various conditions.

A power transmission roller assembly includes a power transmission roller configured to be brought into contact with the driving roller and the driven roller, a pivot shaft fixed to a vehicle body, a pivot arm arranged radially inside of the power transmission roller and pivotally mounted on the pivot shaft, and a roller support bearing rotatably supporting the power transmission roller. A pair of biasing members are mounted to the pivot arm and bias the roller support bearing to a predetermined position between the driving roller and the driven roller such that the abutment force between the driving roller and the power transmission roller is balanced with the abutment force between the driven roller and the power transmission roller. Sliding members are mounted on respective shafts of the biasing members to extend through the sliding members, and frictional forces are generated between the sliding members and the respective shafts.

A power transmission roller assembly includes a power transmission roller configured to be brought into contact with the driving roller and the driven roller, a pivot shaft fixed to a vehicle body, a pivot arm arranged radially inside of the power transmission roller and pivotally mounted on the pivot shaft, and a roller support bearing rotatably supporting the power transmission roller. A pair of biasing members are mounted to the pivot arm and bias the roller support bearing to a predetermined position between the driving roller and the driven roller such that the abutment force between the driving roller and the power transmission roller is balanced with the abutment force between the driven roller and the power transmission roller. Sliding members are mounted on respective shafts of the biasing members to extend through the sliding members, and frictional forces are generated between the sliding members and the respective shafts.

A water shield structure for a transportation device and the transportation device having such a water shield structure. The transportation device is preferably a self-balancing device and may include a friction drive motor. The water shield structure helps reduce the entry of moisture from a riding surface into the wheel envelope or drive mechanism of the device. The water shield structure may extend laterally from a wheel and be enclosed, at least in part, in a housing.

A power transmission roller assembly is provided which includes a roller body to be brought into abutment with the driving roller and the driven roller; a pivot shaft fixed to a vehicle body; a pivot arm provided radially inside of the roller body, and pivotally mounted on the pivot shaft; a roller support bearing rotatably supporting the roller body; and a pair of biasing members provided on the pivot arm. The pair of biasing members bias the roller support bearing to a predetermined position between the driving and driven rollers where the abutment forces between the roller body and the driving and driven rollers balance with each other.

A power transmission roller assembly is provided which includes a roller body to be brought into abutment with the driving roller and the driven roller; a pivot shaft fixed to a vehicle body; a pivot arm provided radially inside of the roller body, and pivotally mounted on the pivot shaft; a roller support bearing rotatably supporting the roller body; and a pair of biasing members provided on the pivot arm. The pair of biasing members bias the roller support bearing to a predetermined position between the driving and driven rollers where the abutment forces between the roller body and the driving and driven rollers balance with each other.